$ git clone -n https://src.fedoraproject.org/rpms/f36-backgrounds.git /var/lib/mock/f45-build-8609-392/root/chroot_tmpdir/scmroot/f36-backgrounds
Cloning into '/var/lib/mock/f45-build-8609-392/root/chroot_tmpdir/scmroot/f36-backgrounds'...
$ git fetch origin 5ceb675f6ef90169f1eece0275988c97c5fd2804:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/f36-backgrounds
 * [new ref]         5ceb675f6ef90169f1eece0275988c97c5fd2804 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5ceb675 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild